Method of separating sludge from liquid hydrocracked products



METHOD 0F SEPARATING SLUDGE FROII LIQUID HYDROCRACKED PRODUCTS Filed 001'.. 6, 1958 United States Patent O Our invention relates to an improvement in the hydrocracking of asphalt-containing petroleum residual fractions to produce lower boiling materials such as gasoline and the like.

lt has heretofore been proposed -to hydrccrack asphaltcontaining petroleum residual fractions by passing such fractions together with hydrogen into contact with a hydrogenaticn catalyst under elevated conditions of temperature and pressure to produce gasoline and the like. ln hydrocracking, it is desirable to operate at relatively mild conditions of pressure, in order to reduce capital and operating costs, and it is also desirable to recycle the residual portion ofthe hydrocracked product, in order to produce as much gasoline and the like from a given quantity of fresh feed. In hydrocracking asphalt-containing petroleum residual fractions under relatively mild conditions of pressure yand with recycling, it is found, however, that undue fouling and plugging of the reaction system takes place.

in accordance with our invention, We have discovered that the liquid hydrocracked product can be conveniently separated into two fractions, the rst of which is a desirable feed to the hydrocracking zone in that it is of low tendency to cause fouling and plugging, and the second of which is a sludge and is an undesirable feed to the hydrocracking zone, having a high tendency to cause fouling and plugging in comparison with the hydrocracked product from which it is derived. This separation can be accomplished in a variety of ways, as by simple settling.

Hence, our invention is an improved process for hydrocracking asphalt-containing petroleum residual fractions in which such a fraction is hydrocracked by passing it under hydrocracking conditions of temperature and presure and in admixture with hydrogen into contact with a hydrocracking catalyst. The feed Ito our process can be, for exmple, a residue resulting from the distillation of crude petroleum. Gn the other hand, we can employ asphaltic materials which are precipitated in the propane treatment of a crude residue containing asphalt.

Any of the catalysts conventionally employed in the hydrccracking of `heavy petroleum oils can be utilized in accordance with the present process. Examples of suitable catalytic ingredients are molybdenum, tungsten, vanadium, chromium, cobalt, nickel, iron and tin and their oxides yand sudes. Mixtures of these materials or compounds or two or more of the oxides can be employed. For example, mixtures or compounds of the iron group metal oxides or sultides with the oxides or suldes of group Vl left column of the periodic table constitute very satisfactory catalysts. Examples of such mixtures or compounds are nickel molybdate, tungstate or chromate (or thiomolybdatc, thiotungstate or thiochromate) or mixtures of nickel oxide with molybdenum, tungsten or chromium oxides.

These catalytic ingredients can be disposed on or carried by known cracking catalysts of the solid refractory llild Patented jan. i904 ICC type. Suitable catalysts of this type are silicates or mixtures of silicates or mixtures of oxides which are known to be cracking catalysts. Snythetic cracking catalysts of this type will generally be mixtures of hydrous oxides of silicon with one or more of the oxides of magnesium, boron, aluminum, titanium or zirconium. Natural cracking catalysts of this type are usually silicates of magnesium and/ or aluminum combined with minor amounts of oxides of these metals which may or may not be activated as by acid treatment. Speciiiic examples of suitable so-lid refractory cracking catalysts are natural or synthetic Ifluoride-promoted alumina, silica-alumina, silicamagnesia, Zirconia-silica, titania-silica, alumina-Zirconiasilica, alumina-boria-silica `or alumina-magnesia-silica cracking catalysts. The catalytic ingredients can be dispersed on or composited with the base in any conventional rnanner, for exam-ple by impregnating it with a suitable solution of a salt followed by drying and calciuing to convert the salt to the oxide.

T he hydrocracking step of the process of our invention is carried out under relatively mild pressure conditions generally from 750 p.s.i.g. to 1200 p-.s.i.g. The temperature used in the hydrocracking zone will generally be from 750 F. .to 850 F. and preferably from 800 F. to 840 F. The hydrocracking is carried out with hydrogen being introduced into the hydrocracking Zone, and the amount of hydrogen introduced is generally Within Ithe range from 3,000 to 10,000 standard cubic feet per barrel of rfresh feed. Also, the amount of hydrogen consumed in the hydrocracking step of our invention is generally within the ran-ge from 300 to 2,000 standard cubic feet per barrel of fresh feed. The Weight hourly space velocity (Vi/HSV, weight units of oil introduced into the reaction zone per weight unit of catalyst per hour) will generally be within the weight range from 0.3 to 3.0, based upon the amount of the fresh feed.

From the liquid hydrocracked product there is separated a rst fraction which is a desirable feed to the hydrocracking zone and this fraction, or a portion thereof, is recycled, generally in amounts such that the weight o-f the material inthe rst fraction boiling at 950 F. and above is from one-half -to one times the weight of the fresh feed. Also, from the liquid hydrccracked product there is separated a second fraction which is a sludge and which is an undesirable feed to the hydrocracking zone, in comparison with the mixture yfrom which it is derived. This second fraction is not recycled to the hydrocracking zone. The separation can be effected, if desired, by simple mechanical separation, for example, hot filtration, centrifuging or settling. Also, prior to or during mechanical separation there can be added to the liquid hydrocracked product a small amount o-f a occulating agent, such as boron trilluoride-ether complex, to aid in the formation of sludge. ln addition, prior to or during mechanical separation a small amount of a light hydrocrabon liquid can be added to the liquid hydrocracked product to laid in the formation of sludge. Using the aforementioned techniques, 'the sludge can be separated from full range liquid hydrocracked product or 'from a residual fraction thereof, for example, material boiling above the gasoline range, or above the gas oil Irange. The separation of the sludge can be carried out under a wide range of temperature conditions, generally from about F. to 500 F., the particular temperature chosen in practice depending in part upon the viscosity cf the liquid hydrocracked'product from which the sludge is being separated.

In accordance with our invention, We have found that particular 4advantage is derived in the embodiment thereof wherein the sludge is formed by a combination of settling and the addition of boron triuoride-ether complex to the liquid hydrocracked product. Thus, when this particular sludge-forming technique is used, the `amount of sludge formed is increased and the remainder of the hydroc-raoked product is of lower asphaltene and metal content. Tables l and Il set forth the results obtained in hydrocracking a sample of Iasphalt feed in two runs using a cobalt oxide-molybdenumoxide-alumina catalyst. In Table I the following hydrocracking conditions were used: temperature, 816 F.; pressure, 950 p.s.i.g.; hydrogen feed rate, 5,940 standard cubic feet per barrel of fresh feed; hydrogen consumption, 525 standard cubic feet per barrel of fresh feed; and weight hourly space velocity, 0.99, In Table Il, the following hydrocracking conditions were used: temperature, 822 F; pressure, 955 p.s.i.g.; hydrogen feed rate, 7,000 standard cubic feet per barrel of fresh feed; hydrogen consumption, 700 standard cubic feet per barrel of fresh feed; and weight hourly space velocity, 0.74.

,4 cooling means not shown and which is operated at substantially the same pressure as reactor 1. Unconsumed hydrogen as well as certain volatile constituents of the hydroeracked product, such as C1 Ito C3 hydrocarbons, hydrogen sulde, ammonia and water, are removed overhead from flash drum 6 by means of line 7 and recycled by means of lines 0 `and 3 to reactor 1. In order to prevent excessive build-up of volatile constitutents of the hydrocracked product in ythe hydrocrack-ing Zone, release gas line 9 is provided. Make-up hydrogen is introduced through line 10, as needed.

Liquid hydrocracked product is removed from flash drum 6 by means of line 11 at the rate of 1840 barrels per day and this is introduced into settler 12 together with l percent by weight of boron tri-iluoride-ether complex based upon the Weight 4of the liquid pasisng through line 11, the boron triuoride-ether complex being introduced by means of line 13. Settler 12 is operated in such manner that three phases are present therein, namely, an upper vapor phase which is removed by means of line 14, an intermediate layer of liquid hydrocracked products from which sludge has been separated which is removed by TABLE I n-Cs Yields API Percent Percent Percent insol. NiO V205 Stock (Wt. C H S (W t. (ppm.) (ppm.) Per- Percent) cent) 400 F-l- Hydrccracked Pr0duct 100 12. 7 86. 77 10. 89 1. 09 16. 5 88 200 Settling at 250 F. with 1% BFS- Ether Complex Added:

Decanted Material 83 14.1 87.05 11. 19 0. 90 12. 8 60 130 Sludge 17 Asphalt Feed 9. 7 86. 30 10. 74 1. 28 13. 7 100 100 TABLE LI I1-C5 Yields API Percent Percent Percent insol NiO V205 Stock (Wt. C H S (Wt. (ppm.) (ppm.) Per- Percent) cent) 950 F.l Hydrocracked Product 100i 4. 9 87. 20 10. 06 1. 35 20. 3 138 370 Settling at 250 F. with 1% BF- Ether Complex Added:

Decanted Material"- 77 6. 5 87. 41 10. 46 1. 39 24. 1 98 240 Sludge 215 620 Asphalt Feed 100 300 The following example illustrates the invention and is to be considered together with the accompanying drawing, Which shows an arrangement of `apparatus in which our invention can be carried out.

Example Asphalt feed at the rate of 1000 Ibarrels per day, hydrogen gas `at the rate of 6000 standard cubic feet per barrel of asphalt feed and recycle bottoms at the rate of 800 barrels per day `are introduced into hydrocracking reactor 1 by means of lines 2, 3 and 4, respectively. Reactor 1 is provided with a bed of supported cobalt molybdate catalyst pellets lanalyzing 2.62 Weight percent cobalt, 9.65 Weight percent M003, 80.89 weight percent `alumina and 5.5 weight percent silica. The amount of catalyst present in reactor 1 is such that the Weight hourly space velocity is 0.5, `based upon fresh asphalt feed. The temperature in reactor 1 is 815 `F. and the pressure is 1000 p.s.i.g. `\By operating in this manner, hydrogen consumption is approximately 1000 standard cubic feet per barrel of fresh asphalt feed.

Hydrocraoked product, together with unconsumed hydrogen, is removed from the bottom of reactor 1 by means of line 5 and is introduced into flash drum 6, which is maintained -at a temperature of approximately 200 F. by

means of line 15, and a lower sludge layer which is red moved -by means of line 16.

The vapors passing through line 14 and the sludge-free liquid hydrocracked product passing through line 15 are introduced into distillation zone .17, which is composed of a series of fractionating columns including a vacuum still. As separate overhead products from distillation zone 17, there are recovered boron lluoride-ether complex, light gasoline, naphtha, distillate fuel, and gas oil, through lines 18, 19, 20, 2l and 22, respectively'.

The sludge passing through line 16 is introduced into -boron trilluoride-ether complex recovery vessel 23, which is heated so as to maintain it at a temperature of 300 F.

Boron trifluoride-ether complex pass overhead from ves# sel 23 through line 24, :is admixed with similar material passing through line 18, and is then introduced into settler 12 using line 13. From the lbottoni of vessel 23 lthrough line 25 there is removed 120 barrels per day of sludge which is useful as fuel.

Bottoms are removed from the vacuum still which forms a part of distillation zone 17 using line 26. Of these bottoms 800 barrels a day pass through line 4 and excess is removed by means of line 27.

Table HI sets forth information concerning the asphalt feed and the products produced when the operation of the example is carried out.

TABLE III Products Sludge Asphalt Btms. Identity Feed Yd. or

Gasoline Naphtha Distillate Gas Oil Recycle Solid Liquid Portion Portion Specific Gravity 60/60 1. 0021 1.25

API 9. 7 68. 7 53. 2 34. 33 22. 5 6. 5 6.5 Penetration at 77 F 265 R. & B. Soit. Pt., "F 101 Viscosity;

SUS/122 F--. 178. 7

SFS/210 F 610 Con. Carbon Res., Wt., percent 19. 33 0.27 C5 Insol., Wt., percent 13. 62 24.1 38. 85 24.1 Viscosity, SUS/210 F--. 141. 5 Carbon, Wt., percent. 86. 30 87.41 87.00 87. 41 Hydrogen, Wt. percent. 10. 74 10. 46 8. 54 10. 45 Sulfur, Wt., percent 1. 28 0.27 0. 37 0.60 0 8l 1.39 1` 42 1. 39 NiO, ppm 100 0.39 112 270 112 V205, p.p.m 300 0.72 280 520 280 Brornine No 9, 5 24. 4 26. 3 Octane;

RM 3 cc. TEL 73. 5 52. 0 Cetane No- 45. 9

It is claimed:

1. In the hydrocracking of a petroleum residual fraction containing asphalt to produce lower boiling materials by passing the residual fraction and hydrogen `into contact with a solid hydrooracking catalyst under hydrocracking conditions of temperature and pressure, the steps of introducing boron triluoride-ether complex into the resid-ual fraction of the liquid hydrocracked product, separating sludge from said residual fraction and returning to the hydrocraoking zone together with fresh feed hydrocracked product from which the sludge has been separated and lower boiling materials removed, the hydrocracking being conducted under the following conditions: temperature, 750 to 850 P.; pressure, 750 to 1200 p.s.i.g.; weight hourly space velocity based on fresh feed, 0.3 to 3.0; hydrogen rate based on fresh feed, 3000 to 10,000 standard cubic feet per barrel; and hydrogen consumption rate based on fresh feed, 300 to 2000 standard cubic feet per barrel.

2. .The process of claim l wherein the hydrocracking catalyst is cobalt molybdate supported on alumina.

3. In the hydrocracking of a petroleum residual fraction containing asphalt by passing the residual fraction and hydrogen into contact with a solid cobalt molybdate on alumina hydrocracking catalyst under hydrocracking conditions of temperature and pressure to produce lower boiling materials, the steps of introducing boron triiluoride-ester complex into the liquid hydrocraoked product, distilling the hydrocracked product from which sludge has been separated to remove overhead lower boiling materials and returning bottoms to the hydrocracking Zone together with fresh feed, the hydrocracking being conducted under the following conditions: temperature, 750 to 850 LF.; pressure, 750 to 1200 p.s.i.g.; weight hourly space velocity based on fresh feed, 0.3 to 3.0; hydrogen rate based on fresh feed, 3,000 to 10,000 standard cubic feet per barrel; and hydrogen consumption rate based on fresh feed, 300 to 2,000 standard cubic feet per barrel.

v4. The process of claim 3 in which the bottoms are returned to the hydrocracking zone together with fresh feed in an amount such that the weight of material in said product boiling at 950 and above is from onehalf to one times the weight of the fresh feed.

References Cited in the le of this patent UNITED STATES PATENTS UNTTED STATES PATENT OFFICE oofomu i l E@ Retent No BJHVGTQ January 'l 1964 Donald IM Houenkamp et aL.

It is hereby certified that error appears 1n the above numbered patent requiring convection and that the said Letters Patent should read as eorected below.

Column o? Time 25 after 'produot? insert e separating sludge from seid liquid hydvooreoked poducftY Signed and sealed this 10th dey of November T9641.o

(SEAL) Attest:

ERNEST W, SWIDERv EDWARD J., BRENNER Avttesting fficer Commissioner of Patents 

0.3 TO 3.0; HYDROGEN RATE BASED ON FRESH FEED, 3000 TO 10,000 STANDARD CUBIC FEET PER BARREL; AND HYDROGEN CONSUMPTION RATE BASED ON FRESH FEED, 300 TO 2000 STANDARD CUBIC FEET PER BARREL.
 1. IN THE HYDROCRACKING OF A PETROLEUM RESIDUAL FRACTION CONTAINING ASPHALT TO PRODUCE LOWER BOILING MATERIALS BY PASSING THE RESIDUAL FRACTION AND HYDROGEN INTO CONTACT WITH A SOLID HYDROCRACKING CATALYST UNDER HYDROCRACKING CONDITIONS OF TEMPERATURE AND PRESSURE, THE STEPS OF INTRODUCING BORON TRIFLUORIDE-ETHER COMPLEX INTO THE RESIDUAL FRACTION OF THE LIQUID HYDROCRACKED PRODUCT, SEPARATING SLUDGE FROM SAID RESIDUAL FRACTION AND RETURNING TO THE HYDROCRACKING ZONE TOGETHER WITH FRESH FEED HYDROCRACKED PRODUCT FROM WHICH THE SLUDGE HAS BEEN SEPARATED AND LOWER BOILING MATERIALS REMOVED, THE HYDROCRACKING BEING CONDUCTED UNDER THE FOLLOWING CONDITIONS: TEMPERATURE, 750 TO 850*F.; PRESSURE, 750 TO 1200 P.S.I.G.; WEIGHT HOURLY SPACE VELOCITY BASED ON FRESH FEED, 